Great Plains 2525A Operator Manual - Manual (Page 29)

Great Plains Manufacturing, Inc. Table of Contents Index Operating Instructions 25
2013-06-04 Table of Contents Index 118-999M
Fan General Operating Information
Adjust the fan to provide the meter pressure recom-
mended for the seed disk, seed, and seed density. See
the tables and charts for recommended values in the
Seed Rate Manual.
Normal gauge readings are in the 0.8in to 4.0in water
pressure range, and vary considerably with crop.
Refer to Figure 14
Use tractor remote hydraulic valve flow control to set fan
speed and butterfly valve adjustment to make fine adjust-
ments to meter pressure. Precise technique depends on
tractor capabilities:
• The objective is obtain recommended meter pressure,
and maintain it during end-of-pass marker fold, lift and
turn.
• For any setup adjustment, operate the tractor engine
at typical field rpms, and not at idle.
• Preset the butterfly valve:
If the tractor has fine control of remote flow rates, and
consistent flow at varying tractor engine rpm, initially
set the butterfly valve to 30
°
or less.
If the tractor has only coarse control of flow, initially set
the butterfly valve to 45
°
.
• Set the fan circuit flow to bring the gauge reading to
near the recommended value.
• Fine tune the meter pressure with the butterfly valve.
• If the tractor has marginal flow available, or the list cir-
cuit has priority, you may need to experiment with
combinations of fan flow and butterfly valve settings.
Always start the fan with a low flow setting.
Gradually bring fan up to the recommended initial meter
pressure.
At excessive rpm, too much air flow can cause:
• oil heating
• slow lift times
If desired pressure cannot be reached, or require unusu-
ally high oil flow at low butterfly valve settings, chances
are the fan is running backwards. Reverse the
inlet/return lines at the hitch.
Butterfly Valve Operation:
To adjust, loosen bolt
and rotate the handle .
Re-tighten bolt.
0
°
is wide open - maximum air flow.
90
°
is closed - minimum air flow.
The valve provides the most effect at settings between
20
°
and 70
°
.
Starting at 30
°
reduces the fan workload.
Starting at 45
°
provides the most adjustment range up or
down.
Figure 14
Fan Butterfly Valve Handle
25137
1 2
1
2
20
°
45
°
70
°
Low Population Risk at Turns:
The fan requires up to 4.5 gpm. This figure does not include oil
for lift/lower or oil for marker operation. Aggressive lift/lower
operations, and simultaneous lift/marker operations, can
reduce fan rpm below that needed to pressurize meter disks. If
seed falls out of pockets, low population bands will occur
shortly after turns.
Unless the tractor has generous oil flow capacity, raise/fold
markers before lift, and lift slowly. Watch meter pressure and
tune operations to keep it at planting levels in turns.